Having trouble putting 16w old to bed

Cori

Mommas, maybe you have pointers, advice, tips, tricks for me. We put our LO to bed around 8:00 pm every night. For the past two weeks we have been having trouble. We give bottle and she will usually fall asleep during. We burp her and place in bassinet. Within 5 min she is awake and crying. We will let her cry for a little bit but end up going back in either to put pacifier back in or hold her to soothe back to sleep. We will do this for 30 min or so until she finally falls asleep. She does NOT do this for naps. She’s pretty easy to put down for naps she just doesn’t nap more than 30 min. What are we doing wrong or what could we change when we put her to bed? Is this part of the sleep regression? Once we get her to sleep she will sleep through the night.